1. Field of the Invention
This invention relates to a high performance hair dryer with a low level of noise emission, increase of energy efficiency due to improvements on the aerodynamic performance and improvements resulting of the use of a mixed flow impeller, in other words, radial part and axial part.
2. Description of Related Art
Inside these fans, the airflow is turbulent, what causes the dryer to emit noise during the operation. In some cases, the noise is elevated, what brings discomfort to users, or even hearing health problems.
Due to that, a hair dryer that improves the airflow inside the casing of the dryer was developed, reducing the level of noise emitted during the operation of the equipment. The change of the internal system of the impeller does not affect the external features of the dryer.
Ordinary hair dryers work with an impeller positioned inside its casing, what causes the internal airflow. The impeller draws the air through the back part of the dryer, driving it to the front part. The air, after passing by the fan, crosses an electric resistance that heats it. Thus, the air comes out of the dryer on high speed and heated. The heated air allows accelerating the air evaporation process and moisture removal of the wet hair, such as modeling and conforming the hair.
Home dryers use impellers of the axial type, which draws and impels the air on the parallel direction to the rotation axis. Axial impellers have low compression ability, are used in dryers with low airflow, and power output. In this assembly, the airflow proportionally increases with the increase of rotation of the impeller, until a limit of maximum airflow, where the stalling occurs. From this rotation, any increase on the rotation does not bring any increase to the flow, but it will generate more turbulence and vortexes, what cause noise.
Professional hair dryers, on other hand, require a greater airflow and compression using radial impeller, which draw the air on parallel direction and impel it on the perpendicular direction to the rotation axis.
With the radial impellers, stalling is reduced due to the air being propelled by centrifugal force, thus, impellers can work with greater rotation and, therefore, generate a greater airflow.
Further, there are spiral impellers that draw the air by the sides and tangentially impel the air to the direction of the rotation, to the front of the hair dryer. In this case, the motor and impeller are perpendicularly mounted to the airflow. These impellers are disused and its operating principle is very similar to radial impellers.